Good Question: ‘Reply All’ On Fall Colors

MINNEAPOLIS (WCCO) — Fall in Minnesota is always beautiful, but this year the colors are especially vivid due to a wet early-mid summer and a sunny fall.

According to the Department of Natural Resources’ fall color map, the Twin Cities haven’t yet reached peak, up North is past peak and much of greater southern Minnesota is right at peak.

This week, Heather Brown is digging into the mailbag to answer your Good Questions about autumn leaves.

Jay asked: “Which tree has the last green leaves in Minnesota?”

According to Lee Frelich, a forestry expert with the University of Minnesota Extension, the answer is oaks … if you are only talking about trees native to Minnesota. But if we were to include the many non-native trees, he believes it would by the Norway maple or Littleleaf Linden.

Frelich says many of Minnesota’s non-natives trees hail from Northern Europe, where they are accustomed to longer periods of daylight. The amount of sun a tree is exposed to is a huge factor when it comes to changing color.

Sue from St. Cloud asked: “Why does the same kind of tree turn colors at different times?”

Frelich says some the same trees that look alike might actually be different species of trees, but if you are sure it’s the same exact kind of tree, it may have something to do with sunlight exposure. Perhaps one tree receives more shade than another.

If you’re talking about the same exact tree in the same exact spot, they can still change colors at different times. Each tree has a different genetic makeup.

“Variability in the genes of each tree means it makes its own decisions to maintain chlorophyll and change color,” Frelich said.

It’s similar to what you might find in people. One woman might be brunette while her sister is blonde.